This invention generally relates to intravascular catheters, such as balloon catheters, for use in the delivery of intravascular stents for repairing body lumens, and more particularly for repairing coronary arteries and peripheral vessels.
It is well known that percutaneous transluminal angioplasty (PTCA) is a widely used procedure for the treatment of coronary heart disease wherein a balloon dilatation catheter is advanced into the patient""s coronary artery and the balloon on the distal portion of the catheter is inflated within a stenotic region of the patient""s artery to open up the arterial passageway and thereby increase the blood flow therethrough. It is also well know that subsequent to PTCA procedures, arteries can abruptly close (abrupt and threatened closure), or more commonly, restenosis can occur over time where the artery tends to re-close due to the growth of cells around the area treated by the PTCA procedure.
A wide variety of repair devices, including intravascular stents, have been used to prevent abrupt or threatened closure and to reduce the likelihood of the development of restenosis. There are numerous intravascular stents manufactured and sold throughout the world with varying degrees of success in reducing the likelihood of the development of restenosis.
Presently, hundreds of thousands of stents are implanted in the coronary arteries and peripheral vessels of patients having some form of vascular disease. One of the problems associated with implanting stents is the ability to deliver the stent on a catheter without the stent coming off the catheter until it is desired to be implanted. In other words, the stent comes off the balloon portion of the catheter prior to reaching the target site, and washes downstream through the patient""s vasculature.
There have been several solutions to prevent the stent from prematurely coming off the catheter, such as a retractable sheath that covers the stent, or collars at either end of the stent to prevent stent movement on the balloon portion of the catheter. Neither of these prior art solutions has been effective for various reasons. Both sheaths and collars can increase rigidity in the distal end of the catheter where flexibility is essential. Further, sheaths and collars may increase the overall profile of the device, also undesirable.
What has been needed, and heretofore not available, is a balloon catheter that is configured to retain a stent on the balloon portion of the catheter during delivery through tortuous coronary arteries, yet maintain flexibility and allow the stent to expand easily away from the balloon portion of the catheter when it is implanted in the vessel. The present invention satisfies these and other needs.
The present invention is directed to an elongated intravascular catheter having an expandable balloon capable of removably retaining a stent thereon.
The catheter of the present invention has an elongated catheter body which includes a proximal end and a distal end and generally has at least one lumen extending therethrough. Typically, there are two lumens extending coaxially through the catheter, one lumen for receiving a guide wire and the other lumen for transmitting inflation fluid to an expandable member, or balloon, located at the distal end of the catheter. The expandable member has a folded configuration and an expanded configuration and expands when the inflation fluid is injected through the catheter and into the interior of the balloon. The balloon has a plurality of preformed grooves extending generally circumferentially around the balloon when the balloon is in the folded configuration. When the balloon is expanded, the grooves flatten out and essentially disappear. When the balloon is deflated, it is not necessary that the preformed grooves re-form, only that they not prevent the balloon from completely deflating so that the catheter and balloon portion can be withdrawn from the patient without catching on any part of the vasculature.
The grooves in the balloon can be further defined as having peaks and valleys, wherein the distance from the peaks to the valleys typically is in the range of about 0.01 mm to 1.5 mm. The grooves generally are uniformly spaced along the longitudinal axis of the balloon, and can define a circumferential or helical pattern along the balloon as well.
In one embodiment of the invention, a catheter assembly is used for delivering and implanting a stent in a body lumen, such as in the coronary arteries or in peripheral vessels. The catheter assembly includes an elongated catheter body having a proximal end and a distal end and typically includes an inflation lumen and a guide wire lumen. The expandable member, or balloon portion of the catheter, has a folded configuration and an expanded configuration and is in fluid communication with the inflation lumen. There are a plurality of pre-formed grooves extending generally circumferentially around the balloon when the balloon is in its folded configuration. The preformed grooves are typically uniformly spaced along the length of the balloon. An intravascular stent is removably crimped over the balloon and is at least partially retained thereon by the grooves as the stent closely follows the contour of the grooves. Typically, stents are comprised of metallic tubes having deformable metal that will conform to the grooves along the length of the balloon.
In another embodiment of the invention, a catheter assembly is used for delivering and implanting a stent in a body lumen, such as in the coronary arteries or in peripheral vessels. The catheter assembly includes an elongated catheter body having a proximal end and a distal end and typically includes an inflation lumen and a guide wire lumen. The expandable member or balloon portion of the catheter has a folded configuration and an expanded configuration and is in fluid communication with the inflation lumen. There are a plurality of preformed grooves extending generally circumferentially around the balloon when the balloon is in its folded configuration. An intravascular stent is removably crimped over the balloon and is at least partially retained thereon by the grooves extending within the matrix of the stent. Typically, intravascular stents are comprised of metallic tubes having a matrix-like structure with a number of openings or holes through the tubular structure. The grooves of the balloon are positioned so that at least some of the grooves extend into the apertures as the stent is crimped onto the balloon.
When the balloon is inflated, the stent expands radially outwardly and the grooves flatten out thereby releasing the stent which is then implanted into the vessel. The balloon is then deflated and the catheter and balloon withdrawn from the patient""s vasculature. The grooves of the balloon define an outer surface which can be identified as peaks and valleys. The outward radial distance between a peak and a valley can vary and typically is in the range of about 0.01 mm to 1.5 mm. In this embodiment, the grooves generally are uniformly spaced along the length of the balloon and can define a helical pattern as well.
The balloon of the present invention can be formed from a polymeric material, such as for example, nylon, PEBAX (polyamide block co-polymer) polyethylene, polyethylene terephthalate and other relatively inelastic polymers and other materials.
The catheter assembly of the present invention can include catheters of the rapid-exchange type in which the guide wire lumen extends through a portion of the catheter, typically through the distal portion of the catheter and having a guide wire exit port located on the catheter proximal to the balloon. The catheter assembly of the present invention also can be of the over-the-wire type, in which the guide wire lumen extends through the catheter from its proximal end to its distal end.
The improvements of the present invention are applicable to a wide range of elongated intravascular catheters which are at least 90 cm in length and which are percutaneously introduced and advanced within a patient""s vascular system, such as the coronary arteries. It is particularly suitable in all types of stenting procedures and can be used with a wide variety of intravascular stents. These and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings.